You'd have to measure how many drops per ml your dropper makes. If you're using the little sample-sized bottles from Purevapes.com - which make about 33 drops per ml - you can add 1 drop of flavoring to 6ml of your nic for 0.5% flavoring, or 1 drop of flavoring to 3ml of your nic for 1% flavoring.
I would never ever make 30ml of juice with flavoring I didn't know I love! I always recommend making the smallest possible batch when trying new flavors.
I like 1% Bilberry, 0.5% Fresh Cream, 0.5% Meringue a lot. That's sweet, creamy, strong blueberry.
You might find something useful here for whatever blueberry you like best:
http://vapingunderground.com/threads/my-notes-on-flavourart-bilberry.2720/
I wrote there that I hadn't tried others, but I have had TFA's Wild Blueberry. I used that successfully in bakery recipes long ago, but with FA Bilberry, I no longer have much use for that TFA flavor.